Why does Antonio compare himself to "the weakest fruit on the tree?"

The line comes from act 4, scene 1 of The Merchant of Venice. Antonio is very depressed at the imminence of his shedding blood, his repaying of the debt to Shylock. It's clearly hit home to Antonio just how serious this is, and just what a foolish mistake he made in concluding such a strange bargain. As he watches Shylock gleefully sharpen his knife he knows that, ultimately, this is all his fault. Bassanio, however, tries to cheer up poor old Antonio, pledging his fervent loyalty to him once more:

Good cheer, Antonio! What, man, courage yet!
The Jew shall have my flesh, blood, bones and all,
Ere thou shalt lose for me one drop of blood.

But Antonio still remains downbeat. He longs for death and reluctantly accepts his fate:


I am a tainted wether of the flock,
Meetest for death. The weakest kind of fruit
Drops earliest to the ground, and so let me.
You cannot better be employed, Bassanio,
Than to live still and write mine epitaph.



In agreeing to the bargain with Shylock, Antonio believes himself to have shown great weakness. And just as the weakest fruit is the first to fall to the ground, so Antonio must be allowed to die. Bassanio, as we've already seen, has just pledged to sacrifice himself before any harm should come to Antonio. But Antonio no longer feels himself worthy of such unstinting loyalty and so tells Bassanio that the best thing he can do is to live on and write Antonio's epitaph.